A Detailed Model for Contemporary GPU Memory Systems

Abstract

This paper explores the impact of simulator accuracy on architecture design decisions in the general-purpose graphics processing unit (GPGPU) space. We enhance the most popular publicly available GPU simulator, GPGPU-Sim, by performing a rigorous correlation of the simulator with a contemporary GPU. Our enhanced GPU model is able to describe the NVIDIA Volta architecture in sufficient detail to reduce error in memory system counters by as much as 66×. The reduced error in the memory system further reduces execution time error by 2.5×. To demonstrate the accuracy of our enhanced model against a real machine, we perform a counter-by-counter validation against an NVIDIA TITAN V Volta GPU, demonstrating the relative accuracy of the new simulator versus the previous model. We go on to demonstrate that the simpler model discounts the importance of advanced memory system designs such as out-of-order memory access scheduling. Our results demonstrate that it is important for the academic community to enhance the level of detail in architecture simulators as system complexity continues to grow.